A Peculiar Story

[chally72]

So I received my new TPS last Friday after running for a few days without it. I put it on the car and went out for some fun. I ran the car as hard as I've ever run her, with a few long pulls at 10-12 psi. I left my buddy's house to pick up my girlfriend at UCONN, and I decided to start taking it easy on her. I noticed halfway into the drive that my AFR was climbing sky-high at idle! On top of that, I heard a whooshing when on boost now.

Ok, no problem. Popped a line. Pulled into a gas station, opened the hood. No popped lines. Anywhere. Wtf?! Since UCONN was between me and my house, I picked my girlfriend up on the way. I had to idle her for a while to get through traffic, and when I popped the hood in a parking lot, my headers were glowing faintly red. Uh-oh. I let her cool down, waited until 10pm, and made the run home without letting it get down to idle. AFR stayed in the 12's-13's, thanks to me having my laptop and putting in a quick safe tune to the Ostrich unit.

The next day, I looked her over very carefully. Checked all the hoses, everything. It all is nice and snug. I start her up, AFR is perfect at idle. WTF! After a 5 minute ride, still perfect. I romp on her a bit, and bam, AFR is up again. Take her home and scratch my head.

What was happening, which I discovered through mostly **** luck, partly through a IR temp gage, is that when I romped on it, underhood temperatures went up about 50 degrees. That intake apparently expands like crazy, as does the turbo intake housing. With my Garrett turbo only having about .050" clearance from the intake cold, it was turning to zip at normal engine temps. And when it heated up a bit more, it acted like a pry bar and lifted the intake away from the head and broke the seal from the intake gaskets! Let it cool down completely for a few hours, and the intake gaskets would reseal themselves. Bolts would stay tight, and I would stay puzzled. What clued me in to this was a slight gas stain from the #2 cylinder, when the fuel was pushed out past the gasket when on boost.

I ended up grinding down the tab on the turbo even more to make clearance, as well as machining the pad on the throttle body that the bottom vacuum fitting goes into. This gave me an extra .120" of clearance. A night of fun hasn't caused a further leak.

This was a crazy one guys!

[carlege]

Interesting. Glad you found the cause

[running_cold924]

what turbo or housing were you running?

[chally72]

Turbo is a Garrett T3/T4R DBB with TO4E compressor housing. Same one Nize currently has on his car.

[minho78]

Originally Posted by chally72

Turbo is a Garrett T3/T4R DBB with TO4E compressor housing. Same one Nize currently has on his car.

So where are you located in CT? What's your comments on the BB turbo?

[chally72]

I'm in the northeastern corner, about 15 minutes outside of Willimantic.

I can count the full throttle pulls on just fingers and toes right now, but my impressions are all extremely positive. 15psi comes in at around 2800 RPM, and you definitely won't run out of air if you want to turn the boost up. Turbo was very easy to turn by hand, and you can hear it wind down for about 15 seconds after the car shuts down. Not much friction there.

To play devil's advocate, the only 951 experience I have to compare it to is an old lindsey super series, oil cooled only, which had significant play in the shaft.

Overall I'm extremely happy with the purchase, and looking forward to messing around with the timing maps when everything is sorted to really unlock some power.

[nize]

wow, glad you figured this one out chally. i'll have to double-check mine next time i have the intake off. the clearance sure is tight there!

[chally72]

Nize, my turbo ended up clocked with that uppermost lug an inch or so to the left. This left it directly underneath that vacuum fitting in the throttle body. You probably have quite a bit more clearance.

I'll post some pictures up later showing what I had to do to things to clearance them. If there is still a problem, I'm going to fly-cut a taper in the mating face of the intake so it sits the throttle body side about .350" higher.

[nize]

i'm curious, why can't you re-clock it to fit better?

[chally72]

My turbo seems to be a bit different than yours in terms of clearances and clocking everywhere, from what I can determine from pictures. I am pretty much locked in to the clocking I have unless I substantially clearance the motor mount around the oil drain for the turbo.

My intake side seems to be much closer to the motor mount than yours was, and it really restricted how it was put on.

Just something to keep in mind for anyone getting one of these turbos....CLOSE to bolt-in, but some assembly reqired!